3B55 Interference & Diffraction of Sound

Speaker and Baffle

A small speaker is much louder when placed behind this baffle.

Speaker and Baffle

Catalog: 
3B55.30
Location: 
Bc2
Music is played through a small, cheap speaker. The speaker is first held in the hand and then placed behind a small hole in a baffle, with dramatic improvement in sound quality.

Moire patterns

demonstration image

Moire patterns

Catalog: 
3B50.40C
Location: 
3_1
Video Encyclopedia :Two transparencies of equally spaced circles on the overhead.

Quincke's Tube

The path of the sound can be lengthened on one side by pulling the slide like a

Quincke's Tube

Catalog: 
3B55.40
Location: 
The sound from a small speaker branches in two directions then out the horn. The length of one of the paths can be changed by pulling the slide like a trombone. The sound will constructively and destructively add as the slide is pulled.